1. Field of the Invention
The present invention relates to a vehicle headlamp that forms a light distribution pattern having a horizontal cutoff line by a reflecting optical system comprising a light source including a semiconductor light emitting unit.
2. Background of the Related Art
In a related art marker lamp for a vehicle, such as a tail lamp, a light emitting diode has often been used as a light source. For example, JP-A-2001-332104, the contents of which is incorporated herein by reference, discloses a marker lamp for a vehicle in which a plurality of lighting units using light emitting diodes as light sources are arranged.
In recent years, the luminance of the related art light emitting diode has been enhanced. Therefore, there is a growing tendency to employ the light emitting diode as the light source of a headlamp for a vehicle.
However, a large number of light emitting diodes have such a structure that an almost rectangular light emitting chip is covered with an almost hemispherical mold lens as described in the above-referenced JP-A-2001-332104. When the light emitting diode is employed as the light source of the vehicle headlamp, various related art problems occur.
For example, but not by way of limitation, in the related art vehicle headlamp, it is necessary to employ a structure in which a light distribution pattern having a horizontal cutoff line can be formed so as not to produce glare to a driver in an oncoming car. In that case, the light distribution pattern is formed as the aggregate of the inverted image of a light source in a headlamp for a vehicle having a reflecting optical system that reflects a light emitted from the light source toward the front part of a lighting unit by a reflector.
At this time, the image of a light emitting chip is greatly deformed, depending on the position of a light incidence on the reflector by the convex lens action of a mold lens. Therefore, a horizontal cutoff line cannot be formed clearly. For this reason, there is a related art problem in that the generation of glare cannot be suppressed effectively.